Book Image

Linux Device Driver Development - Second Edition

By : John Madieu
Book Image

Linux Device Driver Development - Second Edition

By: John Madieu

Overview of this book

Linux is by far the most-used kernel on embedded systems. Thanks to its subsystems, the Linux kernel supports almost all of the application fields in the industrial world. This updated second edition of Linux Device Driver Development is a comprehensive introduction to the Linux kernel world and the different subsystems that it is made of, and will be useful for embedded developers from any discipline. You'll learn how to configure, tailor, and build the Linux kernel. Filled with real-world examples, the book covers each of the most-used subsystems in the embedded domains such as GPIO, direct memory access, interrupt management, and I2C/SPI device drivers. This book will show you how Linux abstracts each device from a hardware point of view and how a device is bound to its driver(s). You’ll also see how interrupts are propagated in the system as the book covers the interrupt processing mechanisms in-depth and describes every kernel structure and API involved. This new edition also addresses how not to write device drivers using user space libraries for GPIO clients, I2C, and SPI drivers. By the end of this Linux book, you’ll be able to write device drivers for most of the embedded devices out there.
Table of Contents (23 chapters)
1
Section 1 -Linux Kernel Development Basics
6
Section 2 - Linux Kernel Platform Abstraction and Device Drivers
12
Section 3 - Making the Most out of Your Hardware
18
Section 4 - Misc Kernel Subsystems for the Embedded World

The I2C driver abstraction and architecture

The struct i2c_driver structure, as we saw in the previous section, contains the driving methods that are needed to handle the I2C devices it is responsible for. Once added to the bus, the device will need to be probed, which makes the i2c_driver.probe_new method the entry point of the driver.

Probing the I2C device

The probe() callback in the struct i2c_driver structure is invoked any time an I2C device is instantiated on the bus and claims this driver. It is responsible for the following tasks:

  • Checking whether the I2C bus controller (the I2C adapter) supports the functionalities needed by the device using the i2c_check_functionality() function
  • Checking whether the device is the one we expected
  • Initializing the device
  • Setting up device-specific data if necessary
  • Registering with the appropriate kernel frameworks

Formerly, the probing callback was assigned to the probe element of struct i2c_driver and...